I have a shader with 2 sources with a texture map for the blender.. I want to add a third source to the mixer/blender. How can I do that

Just for my information, what is the difference between a multi channel mixer and a multi layer shader ? (because in a multi layer, you can specify as many basic layers as you wish, each with its own opacity mask.

Okay heres what I got! I want to add some SA2 Missile near hit damage to my F-4! For all the object involved I have 2 copies that I plan to turn on and off at the appropriate time. I want the Rt Wing, Tail, Rudder and Fuselage to all have copy with all the damage…

On the Rt wing and the 2 ailerons it was easy they only had one SOURCE. The fuselage is another story. it already thad 2 sources as does the rear tail section!

The FUSE has a TEXTURE map Mixer to let the MEtALIC part of the rear/tail end sort of come through and looks worn and discolored somewhat by heat ext. SO it already HAS a texture map to cover up the PAINT and let the metal pop out!

I need another that will not only show the paint but not mess up the metal area at the read AND show the new flak damage which consists on a MASK/TEXTURE MAP MIXER… a HOLE MAP to put an ALPHA for the missing metal… and a BUMP map to simulate bent metal ! SEE WING DAMAGE! PIC

Now the FUSE source 2 uses a metal shader OTHER than the metal shader called ALUMINUM I want to use to show the damage or I could go into the source one and two MASK and modify it.